AWS ElastiCache

ElastiCache improves performance of web applications by allowing you to retrieve info from fast, managed, in-memory system.

Amazon ElastiCache works as an in-memory data store and cache to support the most demanding applications requiring sub-millisecond response times. By utilizing an end-to-end optimized stack running on customer dedicated nodes, Amazon ElastiCache provides secure, blazing fast performance.

FULLY MANAGED
SCALABLE

Using Amazon ElastiCache, you can not only improve load and response times to user actions and queries, but also reduce the cost associated with scaling web applications.
As an example for application session stickiness using Elastic cache
Use if users complain about having to login while using your app.